As is well known, in becoming proficient in the game of golf, it is necessary for the golfer to consistently hit the golf ball from the tee box and fairways with distance and accuracy. Although golf swings vary from golfer to golfer, a proper golf swing from the tee box or fairway entails that the wood or iron be swung in an arcuate fashion, with the momentum imparted to the golf ball by the club head being controlled by the amount of back swing as well as the impact velocity of the front face of the club head upon the golf ball.
With particular respect to "irons", the club head of each iron typically defines a neck portion for attachment to one end of the club shaft, a heel, a toe, a sole, a front striking face, and a rear face. When the sole of the club head is rested upon a horizontal surface, the front face is offset from a vertical axis extending perpendicularly from the horizontal surface by a selected angle commonly referred to as the "loft angle". In this respect, the higher the numerical designation of a particular iron, the greater the loft angle. As will be recognized, the loft angle of the front face of the club head determines the trajectory of the golf ball when the same is properly impacted by the front face.
In the prior art, the club heads of irons are typically produced via an investment casting or forging process wherein a quantity of molten wax is poured into a mold cavity which approximates the shape of the club head. The wax hardens into a wax pattern which is subsequently removed from within the mold cavity and coated with plaster or ceramic via a dipping, spraying, or molding process. Once the coating has solidified into an outer shell, the wax pattern is melted and the wax drained from within the outer shell. Thereafter, a molten metal material such as stainless steel is poured into the outer shell. Upon the solidification of the metal material into the club head, the outer shell is removed therefrom, with the club head subsequently undergoing finish machining operations.
There has been an ongoing effort in the prior art to design club heads for irons wherein the weight is distributed in a manner making the golf club more forgiving by creating a larger "sweet spot", or correcting for slices and/or hooks by imparting spin onto the golf ball which compensates for an improper orientation of the front face relative to the golf ball at impact. To achieve the desired weight distribution characteristics, there has been developed in the prior art club heads for irons which include an extremely hard insert material disposed within the front face and/or rear face of the club head. Typically, such insert is separately formed and subsequently adhesively bonded or mechanically fastened into a recess formed within the front and/or rear face. The use of an adhesive has proven deficient, often times resulting in the hardened insert becoming dislodged due to the high impact forces exerted upon the front face of the club head. Additionally, the use of adhesives between the hardened insert and the club head often serve to dampen the impact forces and thereby reduce the overall length of the golf shot. In this respect, gluing the pre-fabricated insert into the club head, and in particular into the front face thereof, is typically less effective in transferring the load of the gold ball impact to the club head, thus resulting in a loss of feel and distance.
The present invention overcomes the deficiencies associated with prior art club heads for irons by providing a method of manufacturing a club head incorporating a ceramic insert which defines the rear face of the club head and redistributes weight from the center of the front face to the perimeter thereof, thus increasing the size of the "sweet spot" without increasing the overall weight of the club head. In addition to increasing the size of the sweet spot, the inclusion of the insert displaces weight away from the center of the club head, thus increasing the golf club's moment of inertia and making it a better, more forgiving club to hit. In the present manufacturing method, a head body of the club head is cast about the insert in a manner wherein the insert is partially encapsulated by the head body and rigidly captured therewithin. Advantageously, the encapsulation of the insert by the subsequently cast head body mechanically locks the same in place, thus eliminating the need for bonding or secondary attachment methods. Further, the inclusion of the insert within the club head increases the stiffness of the front face thereof. The insert may be selectively located within the club head as desired to improve weight distribution, increase or maintain stiffness of the front face, and improve acoustics (i.e., the sound emitted from a "good hit").